A Model for Mechanism of Peroxyoxalate Chemiluminescence as Applied to Detection in Liquid Chromatography

Abstract

Abstract In recent years, a substantial body of knowledge has been accummulated on the mechanism of peroxyoxalate chemiluminescence (PO-CL). Formal mechanisms have been reported previously by the authors and others purporting to account for the effects of variation of the primary reagents (concentration of oxalate, hydrogen peroxide, and fluorophore) on the peroxyoxalate induced detection of analytes in liquid chromatography and flow injection analyses. In this article, new pathways are suggested also for the induced decomposition of the chemiluminescent intermediate, including: (a) its reaction with a quencher, and (b) its reaction with hydrogen peroxide. Quantitative relationships are derived and established for the effect of pH on the maximum light intensity and the rate of the light decay. The parameters extracted from the experimental data are utilized to predict the influence of reagent concentrations and flow rates on the chemiluminescent detector response. In contrast to the linearity of the relationships in the static solution studies, significant nonlinearities are presented, based on simulations of experimental conditions for flow systems. Among the several conclusions reached, the most important is that the location of the maximum chemiluminescent response in flow systems may not be accomplished by simply determining the optimal values for the individual parameters.